This invention relates to a feed mechanism for a cartridged ribbon used in typewriters or similar printing machines, wherein the feed of the ribbon is effected by driving a feed roller which is operatively connected to the ribbon. The feed roller is driven by a device which is mounted in the machine and which effects a stepped (intermittent) feed of different step sizes dependent upon the type of the ribbon.
In typewriters, data processing apparatuses, or similar machines using ribbon cartridges, generally multiple print textile ribbons, single print carbon ribbons or multiple print carbon ribbons are used. The multiple print textile ribbons are advanced back and forth from one spool to the other or are advanced as an endless ribbon loop and thus repeatedly move past the printing station. The single print carbon ribbons, on the other hand, move through the machine only once, since each surface portion of such ribbons may be utilized only a single time for printing. The mulitple print carbon ribbons too, pass through the machine only once; their individual surface portions, however, are adapted for multiple printing. In case of multiple print ribbons, the magnitude of the feed step (that is, the length of one incremental advance) is of no significance because each surface portion of the ribbon can be utilized repeatedly. In single print ribbons, however, the feed step has to be of such a magnitude that it corresponds to the entire width of the character. In case of multiple print ribbons, on the other hand--for the purpose of an economical utilization--a feed mechanism is needed which effects a feeding step of lesser magnitude.
It is generally known to provide a ribbon feed mechanism which, upon insertion of the respective ribbon cartridge, automatically switches to the operational mode (step length) assigned to that ribbon. Thus, according to U.S. Pat. No. 3,604,549, the cartridge has a configurational characteristic which varies the magnitude of the feeding step as a function of the kind of ribbon contained in that cartridge. The feed roller mounted in the machine is coupled to a ratio-changing transmission gear which is switchable in a positive manner by means of the configurational characteristic of the cartridge. Thus, in one setting of the ratio-changing transmission gear the magnitude of the feed step is such that it corresponds to the width of one character, whereas in another setting the advance of the ribbon is less than the character width and is thus of the overlapping kind relative to the characters.